THURSDAY, July 8 (HealthDay News) -- Early treatment with antiviral drugs appears to help prevent serious illness and death in organ transplant patients with H1N1 swine flu, researchers say.

Because they take immune system-suppressing drugs in order to prevent rejection of their new organs, transplant recipients may be at increased risk for flu virus infection and related complications, the authors of the new study explained in a news release about the study, which was published online July 8 in The Lancet Infectious Diseases.

The study included 237 transplant recipients (154 adults, 83 children) in Canada, Europe and the United States who were infected with the pandemic H1N1 influenza strain A between April and December 2009. The patients had received their transplants a median of 3.6 years before being infected with H1N1 swine flu.

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The researchers said that 167 patients (71%) were admitted to the hospital. Of these, 37 (16%) were sent to the intensive care unit (ICU). Among ICU patients, 21 required mechanical ventilation. Ten of the patients (4%) died.

"Pandemic influenza A H1N1 resulted in a spectrum of illness ranging from mild and self-limiting to severe disease in recipients of solid-organ transplants . . . starting treatment with antiviral drugs early is important for reduction of morbidity and mortality in this highly susceptible population. For example, during periods of transmission, transplant patients presenting with signs and symptoms that are compatible with influenza should probably start empirical treatment with antiviral drugs before the diagnosis is confirmed," wrote Deepali Kumar, of the University of Alberta in Canada, and colleagues.

"Almost a third of the patients in our cohort reported contact with an ill household member before their own illness. In this setting, postexposure chemoprophylaxis might be an option . . . Vaccination of both transplant patients and their household contacts is probably an important preventive measure since vaccine responses might be suboptimum after transplantation," they concluded.